#include <stdio.h>

int fact(int n){
    if(n<1) return 1;
    return n * fact(n - 1);
}

int main(int argc, char *argv[]) {

    int n = 0, k = 0;
    scanf("%d %d", &n, &k);

    int res = fact(n) / (fact(k) * fact(n - k));

    printf("%d", res);
    return 0;
}